Forgive? What's to forgive? There are times when I say to myself "that was stupid, won't do that again" or "you really must get your act together", but I don't recall doing anything which needs forgiving.
(I used to think I would grow out of doing and saying daft things when I got older and grew up, but here I am in my sixties and I don't seem to have grown up at all!)
And as for forgiving myself for something I might do in the future - well, that's a kind of permission to do it anyway!